First Measurements of Pulse Picking by Resonant Excitation (PPRE) at the MAX IV 3 GeV Storage Ring

Abstract

At synchrotron light storage rings there is demand for serving high-brilliance users requesting multibunch operation while simultaneously serving timing users who require single-bunch operation. One method to accomplish this is PPRE developed and currently in user operation at BESSY II. In the method, the transverse emittance of one of the bunches in the bunch train is increased by an incoherent betatron excitation. Part of the light from this bunch can then be separated from the multibunch light by an aperture in the beamline, resulting in single-bunch light for the experiment. Methods such as this expand the scope of storage rings without requiring special fill patterns. This is of growing interest due to the upgrade trend towards diffraction-limited storage rings where it becomes more challenging to operate with inhomogeneous fill patterns. Measurements of PPRE were performed at the MAX IV 3 GeV storage ring utilizing the bunch-by-bunch feedback system both for excitation and as a diagnostic. Furthermore, measurements involving direct beam imaging at the diagnostics beamline allowed quantifying the effect of this excitation on the horizontal and vertical emittance. (Less)